The pair bond in ptarmigan

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Abstract
The three North American ptarmigan species are monogamous, whereas the other six North American grouse species are polygynous. In the Arctic there are few nest predators, which means ptarmigan should be prepared to nest nearer each other than polygynous grouse that lose more nests to predators. Hence, ptarmigan females search relatively small prelaying ranges for nest sites. The small space requirements of females allows males to economically defend with territorial behaviour the nesting resource (cover and space) that females will later search and require, and thus the fitness of males is determined by the quality of the nesting resource that he controls which results in selection by females. In the Arctic the open habitat, continuous daylight, and the presence of effective avian predators have resulted in females also selecting conspicuous, vigilant males in a prolonged pair bond. These males deflect predation risk away from females during nest searching and egg laying in all three species and from hens with chicks in willow ptarmigan.